Many threaded parts and fittings are used in applications requiring a tight seal to be obtained between the threads of the part or fitting and the threads of the system piping. At least two different techniques have been developed for applying sealant to the threads of the fitting.
First, a TEFLON-type sealant tape may be applied to the threads of the fitting. The sealant tape can either be applied by hand, semi-automatically or automatically to a part rotating upon a spindle or mandrel. The tape application is relatively time consuming and may not always be as uniform as preferred. Pieces of the tape may also get into the system to detrimentally affect its performance. A fitting having a sealant tape applied to its threads normally cannot be reused without applying new sealant tape. For example, in a building having an automatic sprinkling system, if the sprinkling head fitting is removed for maintenance purposes, it would normally have the old sealant tape removed from and new sealant tape applied to its threads prior to being reassembled in the system.
The second main sealant application technique for threads of fittings uses paste or liquid type sealants. The paste type sealant is normally hand applied. The liquid type sealant can be dispensed onto a product mounted on a rotating spindle. The liquid sealant when applied to the threads of a vertically oriented fitting, tends to drip lessening the probability of uniform sealant application to the threads. The liquid sealant may also drip into the part fixture and drive mechanism potentially causing maintenance and/or operational problems.
In any type sealant application, it is necessary to seal the threads of numerous fittings having different shapes, thread positions and thread lengths. The hand, semi-automatic or automatic processes presently known for sealing the threads of these various fittings are difficult to adapt from one fitting to another and are relatively time consuming in both process set up and process implementation.